Challenge: find the tach signal wire

[wfo9]

Trying to find a tach signal wire to tap into for some data logging with my wide-band for a future project :gossip:.

I've looked at a few of the wiring diagrams in the download, but can't seem to find anything for the ECU or gauge cluster that specifically labels it.

I'll keep looking, but if anyone has any info or better diagrams... it would be greatly appreciated.

I think it is somewhere in the electrical wiring diagrams found here.
https://www.mediafire.com/?91cliu5r6nb38

But they are not organized very well... and there does not seem to be one for the ECU.. which I know would have it.... I'm starting to wonder if it just uses the crank positioning sensor (which I have found) then sends out the data on the bus or something to the cluster.

[MENTION=66389]BlackWorksInc[/MENTION] if you have any info.... No big rush to find this, but would like to know what I'm looking for before tearing things apart.

 

[e60ral]

Does the RPM reported through the OBD2 interface not refresh fast enough?

Sent from my SM-G930V using Tapatalk

 

[wfo9]

Does the RPM reported through the OBD2 interface not refresh fast enough?

Sent from my SM-G930V using Tapatalk

I'll be scanning also, but this is mainly for correlation and greater granularity. It will be dedicated hardware always recording 25Hz samples of AFR, manifold pressure, and RPM with a 2hr window.

Depends on interface hardware but the OBD stuff is pretty limited on speed with what most of us have. Talking like 2 samples a second once you get a few PIDs in the stream. There are some that can run very fast (like GM enhanced modes...) The standard stuff is pretty useless for tuning or data capture... in general.

New to this on Toyota. So will have more info in the next few weeks.

 

[BlackWorksInc]

That's how it works for most modern engines these days, the crank position sensor sends the data to the ECM which sends it to modules that request the data over the data bus.

 

[wfo9]

That's how it works for most modern engines these days, the crank position sensor sends the data to the ECM which sends it to modules that request the data over the data bus.

Maybe, but I know the FJ had a tach signal wire coming out of the ECU. I would be surprised if they went full data bus on the 5th gen, but possible for sure.

 

[BlackWorksInc]

Maybe, but I know the FJ had a tach signal wire coming out of the ECU. I would be surprised if they went full data bus on the 5th gen, but possible for sure.

I'll double check the wiring diagram, was this a pre-2010 FJ or a newer one?

 

[wfo9]

I'll double check the wiring diagram, was this a pre-2010 FJ or a newer one?

On the pre 2010 I think. I just found info saying the black/white wire on the diagnostic port was the tach signal. I think this was on all the 120 platforms.

If it is that easy.... I just wanted some verification before I started tapping wires... Although I could test the diag port one with no real downside...

 

[BlackWorksInc]

On the pre 2010 I think. I just found info saying the black/white wire on the diagnostic port was the tach signal. I think this was on all the 120 platforms.

If it is that easy.... I just wanted some verification before I started tapping wires... Although I could test the diag port one with no real downside...

Hmm... It does look like a "TACH" pin is on the DLC3 Connector, it should be a Pink wire in Pin#9 (might change color over the years, the diagram I am looking at is for a 2015, TIS is acting up and won't let me properly select years at the moment). Worth a shot? I'm not sure how the data is being transmitted though, so decoding it may be tricky?

 

[wfo9]

Hmm... It does look like a "TACH" pin is on the DLC3 Connector, it should be a Pink wire in Pin#9 (might change color over the years, the diagram I am looking at is for a 2015, TIS is acting up and won't let me properly select years at the moment). Worth a shot? I'm not sure how the data is being transmitted though, so decoding it may be tricky?

Follow up on this..

Thanks [MENTION=66389]BlackWorksInc[/MENTION] it is indeed the pink wire on the DLC3. It is 3 pulses per revolution. This turned out to be easy! Excited to get more data logging now.